Carburetor



CARBURETOR Filed May 9, 1935 5 Sheets-Sheet l Fllllll ram j i 6 vf I 3mm/m HzollzyAJHNSY-UN Jan. 30, A. JOHNSTON Hazz/A JUHNSYN A' Jan. 30, 1934.

H. A. JOHNSTONV 1,945,316

CARBUHETOR Filed may 9, 1953 5 sheets-sheet 3 I 73 n 06, j l v 0 l 722 16 g 26 w 70 16 1 l i ze f2 ,e2

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Jan. 30, 1934.

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H. A. JOHNSTON CARBURETOR Filed May 9, 1935 5 Sheets-Shes?I 4 Jan. 30, 1934- H. A. JOHNSTON CARBURETOR 5 Sheets-Sheet 5 Filed May 9, 1935 JWM HarzjyA. JHNSYN Patented Jan. 30, 1934 UNITED STATES PATENT OFFICE CARBURETOR Calif.

Application May 9, 1933. Serial No. 670,198

21 Claims.

My invention relates to carburetors and more particularly to such devices for use with internal combustion engines.

It is recognized by those who have made researches in this field that an internal combustion engine will run more smoothly and more efficiently if the fuel mixture is supplied to the cylinders in a cool state. This will prevent knocking and jerking and will increase both `the .10 mileage and the top speed of the engine. However, these advantages are lost if the mixture which is supplied is not homogeneous and complete. In carburetors heretofore proposed, it has been found impossible to obtain a proper mixture without supplying heat, and it was very denitely impossible to cool the air and yet cause it to form a good mixture. For this reason the knowledge of the advantages of a cool mixture has been of no practical use.

I have discovered that if air under reduced (subatmospheric) pressure is first caused to assume a whirling motion and then passed by a valve for supplying liquid fuel to the air, a cool yet homogeneous mixture can be formed. Because of the reduction in pressure the mixture is cooled, and yet it is such as to burn freely in the engine. The engine efficiency is thus increased, while the motor runs more smoothly and does not heat up. In effect, the procedure used for making of the mixture at the same time refrigerates or cools it.

This result is accomplished in a novel and simple manner. In the past, carburetors have consisted of a fuel Valve located usually in a Venturi tube and a butterfly valve between the fuel valve and the engine. Fuel must be supplied to the fuel valve by a oat tank which is fed by a fuel pump or vacuum tank. According to my invention, however, the fuel valve is located in a chamber the outlet of which is connected to the intake manifold, while the air controlling valve is located on the inlet side of this chamber. This creates a vacuum in the chamber which is sufficient to draw in the fuel without the aid of any pump or vacuum tank. At the same time, the reduced pressure in the chamber results in a decided cooling of the air and of the resulting mixture.

Homogeneity is produced by giving the air in the chamber a whirling motion so that its turbulence assures a thorough mixing of the fuel with the air. I'he mixture so produced will burn freely and fully in the motor.

A second disadvantage in the usual carburetor D is the jerking or stalling which often accompanies an attempt to accelerate very quickly. 'I'his effect is produced by the rapid opening of the butterfly valve through sudden pressure on the accelerator pedal, which exposes the carburetor to a quick change in suction. One feature of the present invention is a construction which avoids any extremely sudden change in the suction in the vacuum chamber no matter how rapidly the pedal is depressed. Furthermore, this construction will not prevent the motor from accelerating as rapidly as it can with smoothness.

A novel type of choke is also provided. Instead of the usual type, according to my invention operation of the choke control 'opens the fuel feed control valve by an amount which is added to the degree of opening caused by the normal accelerator operation. This Vpermits the choke to be set partly open and so .maintained during operation so as to 'increase the amount of fuel at all speeds. This is a particularly useful feature when fuels of low thermal value are being used.

Furthermore, I have found it desirable in my carburetor, in which the feed of 1 fuel is controlled by a fuel valve, to provide an arrangement which will cause the fuel valve to open in 'a degree corresponding at al1 times and speeds with the opening of the air valve, so that the mixture will always contain the same proportions of fuel and air. This is accomplished by a novel connection between the air valve and the fuel valve.

Another feature of my invention is the provision of an adjustment arrangement between the air valve and the fuel valve which permits a single carburetor to be adjusted so that it will give the desired constant air-fuel ratio with different engines. For instance, low` speed and high speed engines will require `different adjustments to obtain this ratio.

Finally, my carburetor is extremely simple and has relatively .few parts, and therefore can ybe constructed very cheaply. Since no vacuum vtank or pump is required, a further saving is effected. Lastly, the life of the motor and its eiicienc-y 4are greatly increased, 'while jerky motion is avoided.

Further objects and advantages of the invention will appear more fully from the following description when taken in conjunction with the accompanying drawings which form a part there- In the drawings: Fig. 1 is a side elevation of my carburetor. Fig. 2 is a top plan view of the same with the parts in idling position.

Fig. 3 is a similar View of the control levers with the parts in running position.

Fig. 4 is a vertical section on the line 4-4 of Fig. 2 showing the parts in closed or idling position.

Fig. 5 is a cross section showing the parts in operating position, the lower part being on the line 4-4 of Fig. 2 while the upper part is on the line 5-5 of Fig. 3.

Fig. 6 is an end view of the device with the casing partly broken away.

Figs. 7 and 8 are cross sections on the lines 7 7 and 8--8 respectively of Fig. 4.

Fig. 9 is a projection of the air valve.

The carburetor according to my invention comprises an inlet chamber 2 and a mixing chamber 4. These are preferably formed side by side in a single casing. Air enters the bottom of the inlet chamber at 6 while the lower end 8 of the mixing chamber is connected to the intake manifold of the engine. In the Walls of the mixing chamber are formed spiral passages 10 which lead from openings 12 in the wall of the inlet chamber to openings 14 opening into the mixing chamber.

' A vertical shait 16 is rotatably mounted in the top 18 of the inlet chamber and in a guide 20 fixed on the side wall of the chamber. Fixed on this shaft are arms 22 which at their outer ends carry the air valve 24. This valve is curved to conform to the inner' cylindrical surface of the chamber wall and overlies the opening 12. The vshape of this valve and its operation will be described below.

The shaft 16 is provided with an internal bore in which slides a stem 26. This stem is pressed downwardly by a spring 28 which at its upper end rests against a block 30. This block can be f is adjusted to Vary the pressure of the spring on the stem by a screw 32 threaded in the shaft 16. At its Vlower end the stem carries a conical valve member 34 which cooperates with a conical seat -36 around the inlet opening 6. On the lower end of the shaft 16 is an enlarged head 38 which supports an annular cap 40 of leather or the like. This cap is normally gently pressed outwardly by a coil spring 42 bent into annular form. -The upper face of the valve head 34 is provided with an annular ange 44 having an inside diameter substantially equal to the outside diameter of the cap 40. The valve head 34 is pierced by a pin hole 46.

v Near the bottom of the mixing chamber 4 is a horizontal fuel supply pipe 48 which is connected at its outer end vto the gasoline tank or other source. of fuel. This pipe has a reduced opening 50 at its inner end in which engages the idling needle 52 which is threaded in the opposite wall of the chamber. This pipe also has an opening 56 in its upper side and at the center of the mix- `ing chamber. This second opening is controlled by a needle 58 slidable vertically ina sleeve 60 in the top wall 62 of the mixing chamber. This needle is normally pressed downwardly to a position to close the opening 56 by a coil spring 63.

`The movement of the air valve 24 towards clos- -ing position is limited by an idling screw 64 threaded almost tangentially in the wall of the inlet chamber 2. lThis screw engages a lug 66 on the upper arm 22 of the air valve. A stop 68 limits the opening movement of this valve.

The air valve is operated by the accelerator or other speed control element through a lever "i0 mounted on the upper end of the shaft 16. A second lever 72 is likewise mounted on the shaft valve or other restriction in the connecting pas- 16 just above the lever 70. This lever 72 has a split end which can be tightened by a screw '74, thus permitting angular adjustment of the lever on the shaft.

The upper end of the sleeve 60 is surrounded 80 by a vertically slidable sleeve 76 which is normally pressed downward by a spring 78 arranged between shoulders on the two sleeves. The sleeve 76 also has at one side an arm 80 which is connected to the choke button or control by a Bowden cable 82 or the like supported in an arm 84 mounted on the side wall of the mixing charnber. The lower edge of the sleeve '76 has a cut away portion 86, which is cut on a slant to provide a cam surface. A pin 88 is xedly mounted 90 in the top wall of the mixing chamber beneath the cut away portion, the height of this pin being preferably equal to the greatest depth of the cam.

On top of the sleeve '76 rests a link 90 provided 95 with slots 92 and 94. The needle 58 passes through the slct 92 and through a second slot 96 in a plate 98 and carries on its upper end a nut 100 which through a washer engages the plate 98.. The plate 98 rests near one end on `l00 a shoulder 102 formed on the link 90 while at its other end a coil spring 104 is arranged between the link and plate. A pin or bolt 106 mounted in the link 90 and passing through the plate 98 is provided at its upper end with la nut 105 108 which limits the upward movement of plate 98 under the inuence of spring 104. A lock 110 is provided for holding the nut 108 in any position to which it may be adjusted.

The slot 94 in the opposite end of the link 90 310 engages a pin 112 on the lever 72 and is held from longitudinal movement with respect to this pin by a nut 114. The pin 112 is exibly mounted in the end of the lever 72 to permit turning by a ball and socket mounting 116.

The air valve 24, as shown in Fig. 9, has a very special shape. At the top, there is a slightly inclined portion 118 which, even when the valve is in closed position, will let enough air pass to allow the engine to idle. Beyond this portion, 120 the edge extends down at a steep angle as at 120, then shows a bulge or decrease in slope as at 122, and nally has a further almost vertical portion at 124. The purpose of this shape is to give at all degrees of opening of the valve quantities of air proportionate to the degree of opening. While this curve may differ slightly for different types of engines, it will in general have the form indicated. The exact curve can be plotted for any engine by suitable tests with a dynamometer and an analyzer.

The operation of my carburetor will nowbe described. At idling speed, a slight amount of air is drawn through the inlet chamber 2, Athe suction being suiicient to raise the valve 34 135 slightly from its seat against the action of the spring. The air valve 22 is in closed'position,

but air passes over the inclined top edge 118 and sage, and since the passages 10 are largely closed by the air valve 24, the pressure in the mixing lsupply pipe 48 through the idling opening 50.150

The main fuel opening 56 is completely closed by the needle 58. Obviously the idling opening can be regulated by turning the Vneedle -52 A-While vthe setting or the air valve 22 is adjusted by the VSince this plate is inclined its movement will raise the needle and permit fuel to be `drawn through the main fuel opening 56 int'o the mixing chamber. The whirling `motion of the air will insure the formation of a thorough, homogeneous mixture in this chamber.

It an attempt is made to acceleratethe motor too rapidly, the air valve 24 will be openedsuddenly. To prevent any loss of the suction in the motor, I provide the valve 34. If the Vsuction is suddenly increased, a strong force will be eX- erted tending to raise this valve. However, the flange 44 on the valve and 'the leather ring 40 trap a considerable quantity of air which can only escape comparatively slowly through the pin hole 46. These parts act as a dash pot andforce the valve to open relatively slowly. Since the entering air is limited by the position of 'the valve 34, this prevents any sudden rush which would destroy the Vacuum, and gives smooth acceleration at as rapid a rate as is possible.

Although the air valve 24 is so 'proportioned as equally rich mixture, it is quite obvious that, be-

cause of the variation in action Ybetween different motors, some adjustment may be necessary. For this purpose provide an adjusting arrangement which makes any desired regulation possible.

If the quantity of fuel is great enough at low speeds but too low or too high at higher speeds, turning of the nut 108 Will Vary the height of the upper end of the plate 98 and thus remedy any such condition.

If other variation is necessary, it can be {accomplished by releasing the nut 114 and thescrew 74 and turning the lever '72 onthe shaft. When the desired position of the lever is reached, 'the screw 74 is tightened and the nut 114 replaced. Obviously this will result in displacement of the pin 112 in the slot 94, resulting in the condition shown in broken lines in Fig. 2. Since the end of thislever moves in a circular arc, the link 90 will have a substantially harmonic motion. By changing the portion of the arc throughwhich' the lever moves, the relative rate of 'movement of the link can be varied. Thus the link'can be caused to move slowly 'when the air valve begins to open and more' rapidly at the end of its movement or vice versa. Intermediate types of m'otion can also be obtained. In this Way almost any desired regulation can be achieved. For any particular motor, the carburetor is applied and the motor tested at various speeds by'a dynamometer and analyzer. The adjustments above described are then made until an ideal operation is obtained.

The choke operates to raise the link 90 vand thereby the needle 58 to increase the amount of fuel in starting. However, the choke is capable of accomplishing a second purpose. If the fuel being used is low-in energy value, the choke 'can restricting means.

befkept partly opened,`Which Willclearly 'result in a partial opening of 'the needle '-val've "58 'through raising fthe sleeve 7'6. Sinc'ethe link 90 rests on this sleeve, further 'operation of "fthe carburetor will open thef'n'eedl'e valve 'still further. In other Words, "the opening effect -of 'the Thus a constant additional quantity oflovv value fuel-is fed lto the air at all speeds.

It will be evident that 'the mixture formed by A`85 my carburetor is both cool and homogeneous. This will 'result in smoother jengine operation,

cooler running, and increased speed-and mile- Yet my arrangement for producinglthe'se vresults Aisrelatively simple and inexpensive.

i lWhen vin the claims 'I speak of the Aair lvalvelas vbeing in 'iront of the inlet, `-T mean that 4this valve islocated at some l'point Vbetween'theinlet tothe mixing chamber and lthe outside air.

While I have describedher'ein onefembodiment of my invention, 'I Wish it to be understood that I do not intend to limit myself 'thereby'exc'ept within the scope of the appended claims.

5I claim: Y

1. VA carburetor having a fch'ar'nber provided .1100 Witha substantially unrestricted Aoutlet adapted to be connected "to an engine and an "air inlet,

means in iront of said inlet to restrictfthe'ambunt of airiowi'ng into said chamber, means 'to'impa'rt a whirling motion to the air insaid chamber, and :means in said Achamber to -add fuel to the whirling air. f

2. In a carburetor as claimed in claim (1,"m`anually-operable'means to lvary the'p'os'ition ofsaid F10 3. 'In a carburetor 'as claimed 1in claim -rl, a valve controlling 'the opening of 'said inlet, and

frneahs to retard movement of sai'olvalva 4."In a ycarburetor as claimed linclaim 1 a valve controlling the openingof said inlet rand 51315 operated by's'ucti'on in the carburetor, and dash pot means for retarding opening movementof ysaid valve.

V5. vIn a carburetor vas claimed in claim '1, 'a

valve controlling said inlet, spring `mea`ns hor- 1%1'120 inaily urging saidivalve to vclosing position, 'the force of said spring Vmeans being small enough to be overcome by suction inthe carburetor so that the valve v/ill be opened, and dash potime'ans torretard opening movement of the valve. v

6. A carburetor having a mixing chamber provided with a' substantially unrestricted outlet adapted to be connected to an engine kand gan air inlet and spiral passages connected tirsaidr inlet, means in front of said inlet to cont'rol'and restrict the flow of air into said inlet and charnber, jtvh'ereby the pressure-of the airis :reduced andthe air is cooled vand a whirling motiohfimparted thereto, and means in said chamber to add fuel to the cooled, whirling air. y

7. A carburetor having a mixing chamberpro- "vided with an air inlet, a rotatable shaft,"a valve usq- 7o 'of quantities of air proportional at all points to one end on said link, and means to hold the other vend of said plate away from said link.

9. In a carburetor as claimed in claim '7, said cam surface comprising a plate fulcrummed .at one end on said link, means to hold the other end of said plate away from said link, said last means comprising a spring between the second end of the plate and the link, and adjustable means to limit the outward movement of said second end awayirom the link.

10. In a carburetor as claimed in claim 7, said cam surface comprising a plate fulcrummed at one end on said link, means to hold the other end of said plate away from said link, said link having a slot therein near its rst end, a pin kmounted in said lever extending through said slot, and a nut on said pin above said link, said lever being adjustable angularly on said shaft.

11. In a carburetor as claimed in claim 7, said cam surface comprising a plate fulcrummed at lone end on said link, means to hold the other end of said plate away from said link, said last means comprising a spring between the second end of the plate and the link, adjustable means to limit the outward movement of said second end away from the link, said link having a slot therein near its first end, a pin mounted in said lever extending through saidslot, a nut on said pin above said link, said lever being adjustable angularly on said shaft, and chokemeans comprising an element arranged below the second end of said link, and manually controlled means to raise said last element.

12. In a carburetor having fuel supply means and manually operable means to control said fuel supply means, said control means including an element which is moved in accordance with the quantityl of fuel to be supplied, manually operable choke means including means to move said element, the movement caused by said choke means being superimposed on any movement caused by said control means so that said element (is moved a distance equal to the sum of the movements caused by said control and choke means. 13. In a carburetor having a fuel supply pipe provided with an opening, a slidably mounted needle in and controlling'said opening, a movable .element having a cam surface, means on l' said needle engaging said cam surface, manually operable means to move said element to control vthe flow of fuel, and choke means including a rotatable member below saidele'ment having a cam surface thereon, a second vmember engaging` vsaid cam surface, and manually operable means to turn said first member to raise the same and `thereby to raise said element.

y14. A carburetor having a mixing chamber provided with an outlet adapted to be connected to an engine and a cylindrical air inlet chamber and spiral passages connecting said chambers, said spiral passages having inlet openings in the wall of said inlet chamber, a rotatable shaft arranged longitudinally in said inlet chamber, and 'an air valve carried by said shaft. and shaped as "a portion of a cylinder to conform to the inner surface of the wall of the inlet chamber, said air valveoverlying said inlet openings to control the passage of air therethrough.

` 1,5, In a carburetor Vas claimed in claim 14, said '"air valve being so shaped as to permit the passage `the angle through which said shaft is turned.

' 16. Ina carburetor as claimed in claim 14, said air valve being so shaped as to permit the passage of quantities of air proportionalat allpoints to the angle through which said shaft is turned and having a portion cut away at the upper edge to permit idling.

17. A carburetor having a mixing chamber provided with an outlet adapted to be connected to an engine and a cylindrical air inlet chamber and spiral passages connecting said chambers, said spiral passages having inlet openings in the wall of said inlet chamber, a rotatable shaft arranged longitudinally in said inlet chamber, an air valve carried by said shaft and shaped as a portion of a cylinder to conform to the inner surface of the wall of the inlet chamber, said air valve overlying said inlet openings to control the passage of air therethrough, a fuel supply pipe in said mixing chamber, a vertically slidable needle for controlling the flow of fuel from said pipe, said inlet chamber having an air inlet, a valve controlling said air inlet, dash pot means to retard opening movement of said valve, manually operable means to turn said shaft and move said needle, and manually operable choke means.

18. A carburetor having a mixing chamber provided with an outlet adapted to be connected to an engine and a cylindrical air inlet chamber and spiral passages connecting said chambers, said spiral passages having inlet openings in the wall of said inlet chamber, a rotatable shaft arranged longitudinally in said inlet chamber, an air valve carried by said shaft and shaped as a portion of a cylinder to conform to the inner surface of the wall of the inlet chamber, said air valve overlying said inlet openings to control the passage of air therethrough, a fuel supply pipe in said mixing chamber, a vertically slidable needle for controlling the flow of fuel from said pipe, said inlet chamber having an air inlet, a Valve controlling said air inlet, dash pot means to retard opening movement of said valve, manually operable means to turn said shaft, a lever on said shaft, a link connected at one end to said lever and having near its other end a cam surface, means on said slidable element engaging said cam surface, whereby turning of. said shaft moves said slidable needle, said cam surface comprising a plate fulcrummed at one end on said link, means to hold the other end of said plate away from said link, said last means comprising a spring between the second end of the plate and the link, adjustable means to limit ,the outward movement of said second end away from the link, said link having a slot therein near its rst end, a pin mounted in said lever extending through said slot, a nut on said pin above said link, said lever being adjustable .angularly on said shaft, choke means comprising an element arranged below the second end of said link, and manually controlled means to raise said last element, said control means being so proportioned that the ratio of fuel to air is substantially constant at all speeds.

19. A carburetor, adapted for connection to the intake manifold of an internal combustion engine, having a chamber provided with an air inlet, and a substantially unrestricted outlet adapted to be connected to the intake manifold, adjustable means to restrict the flow of air through said inlet, thereby cooling the air within the chamber, means to impart a whirling motion to the air within the chamber, and means for feeding fuel to the cool, whirling air.

20. In a carburetor having fuel supply means and means tc control said fuel supply means, said 'control means including a slidably mounted ele ment which is moved linearly in accordance with Vthe quantity of fuel to` be supplied, a movable ,D

ico

needle in and controlling said opening, a movable element having a cam surface, means on said needle engaging said cam surface, manually operable means to move said element to control the flow of fuel, and choke means including a rotatable member below said element and cam means operable by rotation of said member to raise the same and thereby to raise said element.

HARRY A. JOHNSTON. 

